Caption: Sterile room. Bone marrow transplant patient using an exercise bicycle in his sterile room at the St Louis hospital, Paris, whilst recovering from treatment. Chances of survival in acute leukaemia (bone marrow cancer) and aggressive forms of anaemia have been increased by new techniques of bone marrow transplantation. Treatment is in two stages: first, malfunctioning bone marrow is eliminated through chemotherapy & radiotherapy, and replaced with a graft from a suitably compatible donor. Until the newly-installed immune system is working, the recipient is without means of fighting infection and must remain in a sterile environment for up to three months.